We are developing a magneto-nano sensor protein chip and a multiplex magnetic sorter based on magnetic nanoparticles that allow rapid conversion of discrete biomolecule binding events into electrical signals. These nanotechnologies can detect target molecules down to the single molecule level in less than an hour. Such sensitivity and detection speed are unavailable or impractical with current technologies. The two main components of this project, a magneto-nano sensor chip and a nanoparticle-based magnetic sorter, can operate independently or in conjunction. The maqneto-nano sensor chip will recognize and quantitate protein tumor markers and relevant protein profiles in mouse and human serum samples with unprecedented sensitivity and specificity. These magneto-nano sensors function by exhibiting significant resistance changes which are induced solely by external magnetic fields and are therefore insensitive to solution conditions such as buffers, pH or ionic strength. Biological sensing is accomplished by affinity labeling both the sensor surface and magnetic nanoparticles to simultaneously attach to distinct domains of specifically targeted biological molecules. The magneto-nano sensor then detects the attachment of the biomolecules through the magnetic field induced by the magnetic nanoparticles. For sufficiently small sensors and appropriate magnetic nanoparticle tags, affinity bonding due to a single, specific molecule can be detected as a simple change in the sensor electrical resistance so that expensive excitation sources or remote sensors are not required. The magnetic sorter will rapidly segregate biomolecules. based upon the tunable magnetic properties of the magnetic nanoparticles which bind them, by causing them to deflect at different speeds under a given magnetic field and gradient. In particular, we will be extending technologies to capture and characterize circulating tumor cells from mouse and human serum samples and subsequently analyze the cell lysate for monitoring cancer therapy.